1. Field of the Invention
The present invention relates to a zoom lens and, more particularly, to a micro zoom lens suitably attached to a compact camera such as a lens shutter camera.
2. Related Background Art
The number of automatic functions of compact lens shutter cameras is increasing, and standard functions include an auto focus control, automatic film loading, a date photographing function, and a strobe function. These compact cameras are very popular among people in a wide range. In recent years, a compact lens shutter camera having a multifocal lens has been commercially available, and therefore, the range of users will be further widened.
Simplest zoom lenses suitable for compact cameras of this type are disclosed in Japanese Patent Laid-Open (Kokai) Nos. 56-128911 and 60-170816. Such a zoom lens is a two-group telephoto type zoom lens consisting of a first lens group having a positive refractive power and a second lens group having a negative refractive power. The telephoto type zoom lens does not require a long back-focal distance as compared with a lens for a single-lens reflex camera and is suitable for providing a compact camera by shortening the back-focal distance.
However, a typical conventional zoom lens of this type has a zoom ratio of 1.5 and a focal length f of about 40 to 60 mm, as disclosed in Japanese Patent Laid-Open (Kokai) No. 56-128911. Even a zoom lens having a high zoom ratio has a zoom ratio of 2 and a focal length f of 35 to 70 mm, as disclosed in Japanese Patent Laid-Open (Kokai) No. 60-170816.
In the above zoom lenses, a power (refractive power) of each lens group is weakened so as to assure imaging performance. Therefore, a displacement of each group for variable magnification is increased although the zoom ratio is not so high. As a result, the lens arrangement becomes undesirably bulky.